The method and apparatus of this invention are related to U.S. Pat. No. 4,328,726 entitled APPARATUS AND METHOD FOR WORKING ON SUCCESSIVE SEGMENTS OF SHEET MATERIAL and to copending U.S. patent application Ser. No. 07/571,074 filed Aug. 21, 1990 and entitled METHOD AND APPARATUS FOR ADVANCING SHEET MATERIAL FOR THE CUTTING OF SUCCESSIVE SEGMENTS THEREOF, which patent and copending application illustrate and describe various apparatus and methods for practicing the same general concept as involved in this application of automatically cutting a length of sheet work material segment-by-segment to produce two dimensional pattern pieces or the like. In such segment-by-segment cutting of work material it may happen that a given pattern piece has one portion falling into one segment and another portion falling into an adjacent segment, the first portion being cut while the first segment is at the cutting station and the second portion being cut while the adjacent segment is at the cutting station. It is highly desirable that each pattern piece be cut so as to be completely separated from the waste material, that is with no uncut threads or bridges of work material connecting the pattern piece to the waste material. This requires that the position of the work material relative to the parts of the cutting apparatus be precisely known for each segment of work material brought to the cutting station so that when a pattern piece is cut in two or more portions the beginning and ending points of one portion will precisely register with the beginning and ending points of the adjacent portion.
Since the work material is moved in one coordinate direction, that is the X coordinate direction extending parallel to its length, to advance it segment-by-segment to the cutting station, position errors may occur during each advancement which if uncorrected can lead to the lines cut in one segment not satisfactorily registering with the lines cut in the next adjacent segment. These position errors can arise, for example, because of the work material shifting its position relative to the supporting surface of the conveyor during an advancement, because of the conveyor not following a precisely straight path of movement, or because of the conveyor at the end of the advancement overshooting or undershooting its expected end position.
The general object of this invention is therefore to provide improved apparatus and methods for automatic segment-by-segment cutting of work material whereby good registration of the cutting occurring in adjacent segments of the work material is obtained.
In keeping with the foregoing object, a more detailed object of the invention is to provide an improved apparatus and methods for moving the X beam or carriage of the cutting apparatus in the X coordinate direction in unison with the work material during an advancement to reduce the likelihood of position errors occurring in the X coordinate direction between the work material and the parts of the cutting apparatus, and to provide improved apparatus and methods for detecting and compensating for whatever position errors do occur in either the X coordinate direction or in both the X coordinate direction and Y coordinate direction.
Other objects and advantages of the invention will be apparent from the following detailed description of a preferred embodiment and from the appended claims.